Handheld scanner for rapid registration in a medical navigation system

ABSTRACT

A handheld scanner is provided for use in registering a patient for a medical procedure with a medical navigation system. The handheld scanner has a housing having a main body portion having a first end and a second end and a handle portion having a first end and a second end with the second end attached to the second end of the main body portion with a bridge portion. The handheld scanner further has a circuit board contained in the housing, a processor connected to the circuit board, a light emitter contained in the main body portion and connected to the circuit board, a light detector contained in the main body portion and connected to the circuit board, and a button connected to the circuit board and located on the second end of the handle portion. The button is engageable by a thumb of a hand holding the handle portion.

TECHNICAL FIELD

The present disclosure is generally related to neurosurgical or medicalprocedures, and more specifically to a handheld scanner for rapidregistration in a medical navigation system.

BACKGROUND

In the field of medicine, imaging and image guidance are a significantcomponent of clinical care. From diagnosis and monitoring of disease, toplanning of the surgical approach, to guidance during procedures andfollow-up after the procedure is complete, imaging and image guidanceprovides effective and multifaceted treatment approaches, for a varietyof procedures, including surgery and radiation therapy. Targeted stemcell delivery, adaptive chemotherapy regimes, and radiation therapy areonly a few examples of procedures utilizing imaging guidance in themedical field.

Advanced imaging modalities such as Magnetic Resonance Imaging (“MRI”)have led to improved rates and accuracy of detection, diagnosis andstaging in several fields of medicine including neurology, where imagingof diseases such as brain cancer, stroke, Intra-Cerebral Hemorrhage(“ICH”), and neurodegenerative diseases, such as Parkinson's andAlzheimer's, are performed. As an imaging modality, MRI enablesthree-dimensional visualization of tissue with high contrast in softtissue without the use of ionizing radiation. This modality is oftenused in conjunction with other modalities such as Ultrasound (“US”),Positron Emission Tomography (“PET”) and Computed X-ray Tomography(“CT”), by examining the same tissue using the different physicalprincipals available with each modality. CT is often used to visualizeboney structures and blood vessels when used in conjunction with anintra-venous agent such as an iodinated contrast agent. MRI may also beperformed using a similar contrast agent, such as an intravenousgadolinium based contrast agent which has pharmaco-kinetic propertiesthat enable visualization of tumors and break-down of the blood brainbarrier. These multi-modality solutions can provide varying degrees ofcontrast between different tissue types, tissue function, and diseasestates. Imaging modalities can be used in isolation, or in combinationto better differentiate and diagnose disease.

In neurosurgery, for example, brain tumors are typically excised throughan open craniotomy approach guided by imaging. The data collected inthese solutions typically consists of CT scans with an associatedcontrast agent, such as iodinated contrast agent, as well as MRI scanswith an associated contrast agent, such as gadolinium contrast agent.Also, optical imaging is often used in the form of a microscope todifferentiate the boundaries of the tumor from healthy tissue, known asthe peripheral zone. Tracking of instruments relative to the patient andthe associated imaging data is also often achieved by way of externalhardware systems such as mechanical arms, or radiofrequency or opticaltracking devices. As a set, these devices are commonly referred to assurgical navigation systems.

Three dimensional (3D) sensor systems are increasingly being used in awide array of applications, including medical procedures. These sensorsystems determine the shape and/or features of an object positioned in ascene of the sensor system's view. In recent years, many methods havebeen proposed for implementing 3D modeling systems that are capable ofacquiring fast and accurate high resolution 3D images of objects forvarious applications.

Triangulation based 3D sensor systems and methods typically have one ormore projectors as a light source for projecting onto a surface and oneor more cameras at a defined, typically rectified relative position fromthe projector for imaging the lighted surface. The camera and theprojector therefore have different optical paths, and the distancebetween them is referred to as the baseline. Through knowledge of thebaseline distance as well as projection and imaging angles, knowngeometric/triangulation equations are utilized to determine distance tothe imaged object. The main differences among the various triangulationmethods known in the art lie in the method of projection as well as thetype of light projected, typically structured light, and in the processof image decoding to obtain three dimensional data.

A 3D sensor system may be contemplated as a novel extension of asurgical navigation systems. One popular triangulation based 3D sensorsystem is created by Mantis Vision, which utilizes a single framestructured light active triangulation system to project infrared lightpatterns onto an environment. To capture 3D information, a projectoroverlays an infrared light pattern onto the scanning target. Then adigital camera and a depth sensor, synched to the projector, capturesthe scene with the light reflected by the object. The technology workseven in complete darkness, since it includes its own illumination; inbright environments the quality of the resulting image depends on thehardware used.

During a medical procedure, navigation systems require a registration totransform between the physical position of the patient in the operatingroom and the volumetric image set (e.g., MRI/CT) being navigated to.Conventionally, this registration is done to the position of a referencetool, which is visible by the tracking system and stays fixed inposition and orientation relative to the patient throughout theprocedure.

This registration is typically accomplished through correspondence touchpoints (e.g., either fiducial or anatomic points). Such an approach toregistration has a number of disadvantages, including requiringfiducials to be placed before scans, requiring points to be identified,providing for a limited number of points, touch point collection issubject to user variability, and the physical stylus used for collectingthe points can deform or deflect patient skin position. Anotherconventional approach to collecting the touch points includes performinga surface tracing of the patient drawn as a line which is matched to theimage set surface contour using either a stylus pointer or a laserpointer. Such an approach to registration has a number of disadvantages,including providing for a limited number of points, and the physicalstylus can deform or deflect patient skin position. Yet anotherconventional approach to collecting the touch points includes using amask, which requires a high level of operator training and is operatordependent. This approach also provides only a limited number of points.

Some common limitations exist for conventional 3D scanners used toregister a patient in an operation room. Conventional 3D scanners arenot designed with a surgical team in mind as the intended user and aretherefore not ergonomically suitable for use in an operating room.Further, conventional scanners that use light outside of the visiblespectrum can be difficult to aim because it is not readily apparent whatthe 3D scanner is being directed towards.

Therefore, there is a need for an improved handheld scanner for use in amedical navigation system.

SUMMARY

One aspect of the present disclosure provides a handheld scanner for usein registering a patient for a medical procedure with a medicalnavigation system. The handheld scanner has a housing having a main bodyportion having a first end and a second end and a handle portion havinga first end and a second end with the second end attached to the secondend of the main body portion with a bridge portion. The handheld scannerfurther has a circuit board contained in the housing, a processorconnected to the circuit board, an optional power supply moduleconnected to the circuit board, a light emitter contained in the mainbody portion and connected to the circuit board, a light detectorcontained in the main body portion and connected to the circuit board,and a button connected to the circuit board and located on the secondend of the handle portion. The button is engageable by a thumb of a handholding the handle portion.

A further understanding of the functional and advantageous aspects ofthe disclosure can be realized by reference to the following detaileddescription and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will now be described, by way of example only, withreference to the drawings, in which:

FIG. 1 illustrates the insertion of an access port into a human brain,for providing access to internal brain tissue during a medicalprocedure;

FIG. 2 shows an exemplary navigation system to support minimallyinvasive access port-based surgery;

FIG. 3 is a block diagram illustrating a control and processing systemthat may be used in the navigation system shown in FIG. 2;

FIG. 4A is a flow chart illustrating a method involved in a surgicalprocedure using the navigation system of FIG. 2;

FIG. 4B is a flow chart illustrating a method of registering a patientfor a surgical procedure as outlined in FIG. 4A;

FIG. 5 illustrates a flow chart describing the use of multiple patientreference markers for registration;

FIG. 6 is a flow chart illustrating a method of registering a patientfor a medical procedure with a medical navigation system;

FIG. 7 is another flow chart illustrating a method of registering apatient for a medical procedure with a medical navigation system;

FIG. 8 is another flow chart illustrating a method of registering apatient for a medical procedure with a medical navigation system;

FIG. 9 illustrates a left side view of a handheld scanner for use inregistering a patient for a medical procedure;

FIG. 10 illustrates a front view of the handheld scanner of FIG. 9;

FIG. 11 illustrates a rear view of the handheld scanner of FIG. 9;

FIG. 12 illustrates a top view of the handheld scanner of FIG. 9;

FIG. 13 illustrates a solid perspective view showing the left side ofthe handheld scanner of FIG. 9;

FIG. 14 illustrates a solid perspective view showing the right side ofthe handheld scanner of FIG. 9; and

FIG. 15 illustrates a solid perspective view showing the left side ofthe handheld scanner of FIG. 9 being held by a hand.

DETAILED DESCRIPTION

Various embodiments and aspects of the disclosure will be described withreference to details discussed below. The following description anddrawings are illustrative of the disclosure and are not to be construedas limiting the disclosure. Numerous specific details are described toprovide a thorough understanding of various embodiments of the presentdisclosure. However, in certain instances, well-known or conventionaldetails are not described in order to provide a concise discussion ofembodiments of the present disclosure.

As used herein, the terms, “comprises” and “comprising” are to beconstrued as being inclusive and open ended, and not exclusive.Specifically, when used in the specification and claims, the terms,“comprises” and “comprising” and variations thereof mean the specifiedfeatures, steps or components are included. These terms are not to beinterpreted to exclude the presence of other features, steps orcomponents.

As used herein, the term “exemplary” means “serving as an example,instance, or illustration,” and should not be construed as preferred oradvantageous over other configurations disclosed herein.

As used herein, the terms “about”, “approximately”, and “substantially”are meant to cover variations that may exist in the upper and lowerlimits of the ranges of values, such as variations in properties,parameters, and dimensions. In one non-limiting example, the terms“about”, “approximately”, and “substantially” mean plus or minus 10percent or less.

Unless defined otherwise, all technical and scientific terms used hereinare intended to have the same meaning as commonly understood by one ofordinary skill in the art. Unless otherwise indicated, such as throughcontext, as used herein, the following terms are intended to have thefollowing meanings:

As used herein, the phrase “access port” refers to a cannula, conduit,sheath, port, tube, or other structure that is insertable into asubject, in order to provide access to internal tissue, organs, or otherbiological substances. In some embodiments, an access port may directlyexpose internal tissue, for example, via an opening or aperture at adistal end thereof, and/or via an opening or aperture at an intermediatelocation along a length thereof. In other embodiments, an access portmay provide indirect access, via one or more surfaces that aretransparent, or partially transparent, to one or more forms of energy orradiation, such as, but not limited to, electromagnetic waves andacoustic waves.

As used herein the phrase “intraoperative” refers to an action, process,method, event or step that occurs or is carried out during at least aportion of a medical procedure. Intraoperative, as defined herein, isnot limited to surgical procedures, and may refer to other types ofmedical procedures, such as diagnostic and therapeutic procedures.

Embodiments of the present disclosure provide imaging devices that areinsertable into a subject or patient for imaging internal tissues, andmethods of use thereof. Some embodiments of the present disclosurerelate to minimally invasive medical procedures that are performed viaan access port, whereby surgery, diagnostic imaging, therapy, or othermedical procedures (e.g. minimally invasive medical procedures) areperformed based on access to internal tissue through the access port.

The present disclosure is generally related to medical procedures,neurosurgery, and minimally invasive port-based surgery in specific.

In the example of a port-based surgery, a surgeon or robotic surgicalsystem may perform a surgical procedure involving tumor resection inwhich the residual tumor remaining after is minimized, while alsominimizing the trauma to the healthy white and grey matter of the brain.In such procedures, trauma may occur, for example, due to contact withthe access port, stress to the brain matter, unintentional impact withsurgical devices, and/or accidental resection of healthy tissue. A keyto minimizing trauma is ensuring that the spatial location of thepatient as understood by the surgeon and the surgical system is asaccurate as possible.

FIG. 1 illustrates the insertion of an access port into a human brain,for providing access to internal brain tissue during a medicalprocedure. In FIG. 1, access port 12 is inserted into a human brain 10,providing access to internal brain tissue. Access port 12 may includeinstruments such as catheters, surgical probes, or cylindrical portssuch as the NICO BrainPath. Surgical tools and instruments may then beinserted within the lumen of the access port in order to performsurgical, diagnostic or therapeutic procedures, such as resecting tumorsas necessary. The present disclosure applies equally well to catheters,DBS needles, a biopsy procedure, and also to biopsies and/or cathetersin other medical procedures performed on other parts of the body wherehead immobilization is needed.

In the example of a port-based surgery, a straight or linear access port12 is typically guided down a sulci path of the brain. Surgicalinstruments would then be inserted down the access port 12.

Optical tracking systems, which may be used in the medical procedure,track the position of a part of the instrument that is withinline-of-site of the optical tracking camera. These optical trackingsystems also require a reference to the patient to know where theinstrument is relative to the target (e.g., a tumor) of the medicalprocedure. These optical tracking systems require a knowledge of thedimensions of the instrument being tracked so that, for example, theoptical tracking system knows the position in space of a tip of amedical instrument relative to the tracking markers being tracked.

Referring to FIG. 2, an exemplary navigation system environment 200 isshown, which may be used to support navigated image-guided surgery. Asshown in FIG. 2, surgeon 201 conducts a surgery on a patient 202 in anoperating room (OR) environment. A medical navigation system 205comprising an equipment tower, tracking system, displays and trackedinstruments assist the surgeon 201 during his procedure. An operator 203is also present to operate, control and provide assistance for themedical navigation system 205.

Referring to FIG. 3, a block diagram is shown illustrating a control andprocessing system 300 that may be used in the medical navigation system200 shown in FIG. 2 (e.g., as part of the equipment tower). As shown inFIG. 3, in one example, control and processing system 300 may includeone or more processors 302, a memory 304, a system bus 306, one or moreinput/output interfaces 308, a communications interface 310, and storagedevice 312. Control and processing system 300 may be interfaced withother external devices, such as tracking system 321, data storage 342,and external user input and output devices 344, which may include, forexample, one or more of a display, keyboard, mouse, sensors attached tomedical equipment, foot pedal, and microphone and speaker. Data storage342 may be any suitable data storage device, such as a local or remotecomputing device (e.g. a computer, hard drive, digital media device, orserver) having a database stored thereon. In the example shown in FIG.3, data storage device 342 includes identification data 350 foridentifying one or more medical instruments 360 and configuration data352 that associates customized configuration parameters with one or moremedical instruments 360. Data storage device 342 may also includepreoperative image data 354 and/or medical procedure planning data 356.Although data storage device 342 is shown as a single device in FIG. 3,it will be understood that in other embodiments, data storage device 342may be provided as multiple storage devices.

Medical instruments 360 are identifiable by control and processing unit300. Medical instruments 360 may be connected to and controlled bycontrol and processing unit 300, or medical instruments 360 may beoperated or otherwise employed independent of control and processingunit 300. Tracking system 321 may be employed to track one or more ofmedical instruments 360 and spatially register the one or more trackedmedical instruments to an intraoperative reference frame. For example,medical instruments 360 may include tracking markers such as trackingspheres that may be recognizable by a tracking camera 307. In oneexample, the tracking camera 307 may be an infrared (IR) trackingcamera. In another example, as sheath placed over a medical instrument360 may be connected to and controlled by control and processing unit300.

Control and processing unit 300 may also interface with a number ofconfigurable devices, and may intraoperatively reconfigure one or moreof such devices based on configuration parameters obtained fromconfiguration data 352. Examples of devices 320, as shown in FIG. 3,include one or more external imaging devices 322, one or moreillumination devices 324, a robotic arm 305, one or more projectiondevices 328, a 3D scanner 309, and one or more displays 311.

Exemplary aspects of the disclosure can be implemented via processor(s)302 and/or memory 304. For example, the functionalities described hereincan be partially implemented via hardware logic in processor 302 andpartially using the instructions stored in memory 304, as one or moreprocessing modules or engines 370. Example processing modules include,but are not limited to, user interface engine 372, tracking module 374,motor controller 376, image processing engine 378, image registrationengine 380, procedure planning engine 382, navigation engine 384, andcontext analysis module 386. While the example processing modules areshown separately in FIG. 3, in one example the processing modules 370may be stored in the memory 304 and the processing modules may becollectively referred to as processing modules 370.

It is to be understood that the system is not intended to be limited tothe components shown in FIG. 3. One or more components of the controland processing system 300 may be provided as an external component ordevice. In one example, navigation module 384 may be provided as anexternal navigation system that is integrated with control andprocessing system 300.

Some embodiments may be implemented using processor 302 withoutadditional instructions stored in memory 304. Some embodiments may beimplemented using the instructions stored in memory 304 for execution byone or more general purpose microprocessors. Thus, the disclosure is notlimited to a specific configuration of hardware and/or software.

While some embodiments can be implemented in fully functioning computersand computer systems, various embodiments are capable of beingdistributed as a computing product in a variety of forms and are capableof being applied regardless of the particular type of machine orcomputer readable media used to actually effect the distribution.

According to one aspect of the present application, one purpose of thenavigation system 205, which may include control and processing unit300, is to provide tools to the neurosurgeon that will lead to the mostinformed, least damaging neurosurgical operations. In addition toremoval of brain tumors and intracranial hemorrhages (ICH), thenavigation system 205 can also be applied to a brain biopsy, afunctional/deep-brain stimulation, a catheter/shunt placement procedure,open craniotomies, endonasal/skull-based/ENT, spine procedures, andother parts of the body such as breast biopsies, liver biopsies, etc.While several examples have been provided, aspects of the presentdisclosure may be applied to any suitable medical procedure.

While one example of a navigation system 205 is provided that may beused with aspects of the present application, any suitable navigationsystem may be used, such as a navigation system using optical trackinginstead of infrared cameras.

Referring to FIG. 4A, a flow chart is shown illustrating a method 400 ofperforming a port-based surgical procedure using a navigation system,such as the medical navigation system 205 described in relation to FIG.2. At a first block 402, the port-based surgical plan is imported. Adetailed description of the process to create and select a surgical planis outlined in international publication WO/2014/139024, entitled“PLANNING, NAVIGATION AND SIMULATION SYSTEMS AND METHODS FOR MINIMALLYINVASIVE THERAPY”, which claims priority to U.S. Provisional PatentApplication Ser. Nos. 61/800,155 and 61/924,993, which are all herebyincorporated by reference in their entirety.

Once the plan has been imported into the navigation system at the block402, the patient is placed on a surgical bed. The head position isconfirmed with the patient plan in the navigation system (block 404),which in one example may be implemented by a computer or controllerforming part of the equipment tower.

Next, registration of the patient is initiated (block 406). The phrase“registration” or “image registration” refers to the process oftransforming different sets of data into one coordinate system. Data mayinclude multiple photographs, data from different sensors, times,depths, or viewpoints. The process of “registration” is used in thepresent application for medical imaging in which images from differentimaging modalities are co-registered. Registration is used in order tobe able to compare or integrate the data obtained from these differentmodalities to the patient in physical space.

Those skilled in the relevant arts will appreciate that there arenumerous registration techniques available and one or more of thetechniques may be applied to the present example. Non-limiting examplesinclude intensity-based methods that compare intensity patterns inimages via correlation metrics, while feature-based methods findcorrespondence between image features such as points, lines, andcontours. Image registration methods may also be classified according tothe transformation models they use to relate the target image space tothe reference image space. Another classification can be made betweensingle-modality and multi-modality methods. Single-modality methodstypically register images in the same modality acquired by the samescanner or sensor type, for example, a series of magnetic resonance (MR)images may be co-registered, while multi-modality registration methodsare used to register images acquired by different scanner or sensortypes, for example in magnetic resonance imaging (MRI) and positronemission tomography (PET). In the present disclosure, multi-modalityregistration methods may be used in medical imaging of the head and/orbrain as images of a subject are frequently obtained from differentscanners. Examples include registration of brain computerized tomography(CT)/MRI images or PET/CT images for tumor localization, registration ofcontrast-enhanced CT images against non-contrast-enhanced CT images, andregistration of ultrasound and CT to patient in physical space.

Referring now to FIG. 4B, a flow chart is shown illustrating a methodinvolved in registration block 406 as outlined in FIG. 4A, in greaterdetail. If the use of fiducial touch points (440) is contemplated, themethod involves first identifying fiducials on images (block 442), thentouching the touch points with a tracked instrument (block 444). Next,the navigation system computes the registration to reference markers(block 446).

Alternately, registration can also be completed by conducting a surfacescan procedure (block 450), which may be applied to aspects of thepresent disclosure. The block 450 is presented to show an alternativeapproach. First, the face is scanned using the 3D scanner 309 (block452). Next, the face surface is extracted from MR/CT data (block 454).Finally, surfaces are matched to determine registration data points(block 456).

Upon completion of either the fiducial touch points (440) or surfacescan (450) procedures, the data extracted is computed and used toconfirm registration at block 408, shown in FIG. 4A.

Referring back to FIG. 4A, once registration is confirmed (block 408),the patient is draped (block 410). Typically, draping involves coveringthe patient and surrounding areas with a sterile barrier to create andmaintain a sterile field during the surgical procedure. The purpose ofdraping is to eliminate the passage of microorganisms (e.g., bacteria)between non-sterile and sterile areas. At this point, conventionalnavigation systems require that the non-sterile patient reference isreplaced with a sterile patient reference of identical geometry locationand orientation. Numerous mechanical methods may be used to minimize thedisplacement of the new sterile patient reference relative to thenon-sterile one that was used for registration but it is inevitable thatsome error will exist. This error directly translates into registrationerror between the surgical field and pre-surgical images. In fact, thefurther away points of interest are from the patient reference, theworse the error will be.

Upon completion of draping (block 410), the patient engagement pointsare confirmed (block 412) and then the craniotomy is prepared andplanned (block 414).

Upon completion of the preparation and planning of the craniotomy (block414), the craniotomy is cut and a bone flap is temporarily removed fromthe skull to access the brain (block 416). Registration data is updatedwith the navigation system at this point (block 422).

Next, the engagement within craniotomy and the motion range areconfirmed (block 418). Next, the procedure advances to cutting the duraat the engagement points and identifying the sulcus (block 420).

Thereafter, the cannulation process is initiated (block 424).Cannulation involves inserting a port into the brain, typically along asulci path as identified at 420, along a trajectory plan. Cannulation istypically an iterative process that involves repeating the steps ofaligning the port on engagement and setting the planned trajectory(block 432) and then cannulating to the target depth (block 434) untilthe complete trajectory plan is executed (block 424).

Once cannulation is complete, the surgeon then performs resection (block426) to remove part of the brain and/or tumor of interest. The surgeonthen decannulates (block 428) by removing the port and any trackinginstruments from the brain. Finally, the surgeon closes the dura andcompletes the craniotomy (block 430). Some aspects of FIG. 4A arespecific to port-based surgery, such as portions of blocks 428, 420, and434, but the appropriate portions of these blocks may be skipped orsuitably modified when performing non-port based surgery.

Referring now to FIG. 5, a registration process, similar to that whichmay be used in block 456 of FIG. 4B, is shown for creating a commoncoordinate space composed of amalgamated virtual and actual coordinatespaces. The common coordinate space may be composed of both an actualcoordinate space and a virtual coordinate space, where the actualcoordinate space contains actual objects that exist in space and thevirtual coordinate space contains virtual objects that are generated ina virtual space. The common coordinate space containing both theaforementioned actual and virtual objects may be produced as follows.

In order to form a common coordinate space composed of the amalgamatedvirtual and actual coordinate spaces, the two spaces may be coupled witha “common reference coordinate”, having a defined position that can belocated in both the actual and virtual coordinate spaces. An example ofsuch a common reference coordinate 500 and actual and virtual coordinatespace origins, 510 and 520, are provided in FIG. 5. Once the commonreference coordinate position is acquired in both spaces they can beused to correlate the position of any point in one coordinate space tothe other. The correlation is determined by equating the locations ofthe common reference coordinate in both spaces and solving for anunknown translation variable for each degree of freedom defined in thetwo coordinate spaces. These translation variables may then be used totransform a coordinate element of a position in one space to anequivalent coordinate element of a position in the other. An examplecorrelation can be derived from the diagram in FIG. 5 depicting a twodimensional coordinate space. In FIG. 5, the common referencecoordinates 500 position is determined relative to the actual coordinatespace origin 510 and the virtual coordinate space origin 520. The commonreference coordinates positions can be derived from the diagram asfollows:

(X _(cra) ,Y _(cra))=(55, 55)

and

(X _(crv) ,Y _(crv))=(−25, −45)

Where the subscript “cra” denotes the common reference coordinateposition relative to the actual coordinate space origin and thesubscript “crv” denotes the common reference coordinate positionrelative to the virtual coordinate space origin. Utilizing a generictranslation equation describing any points ((Y_(a), X_(a)) and (Y_(v),X_(v))), where the subscript “a” denotes the coordinates of a pointrelative to the actual coordinate space origin 510, and the subscript“v” denotes the coordinate of a point relative to the virtual coordinatespace origin 520, we can equate the individual coordinates from eachspace to solve for translation variables ((Y_(T), X_(T))), where thesubscript “T” denotes the translation variable as shown below.

Y _(a) =Y _(v) +Y _(T)

Y _(a) =X _(v) +X _(T)

Now substituting the derived values of our points from FIG. 5 we cansolve for the translation variable.

55=−45+Y _(T)

100=Y_(T)

and

55=−25+X _(T)

80=X_(T)

Utilizing this translation variable, any point ((i.e. (Y_(v), X_(v))) inthe virtual coordinate space may be transformed into an equivalent pointin the actual coordinate space through the two generic transformationequations provided below. It should be noted that these equations can berearranged to transform any coordinate element of a position from theactual coordinate space into an equivalent coordinate element of aposition in the virtual coordinate space as well.

Y _(a) =Y _(v)+100

Y _(a) =X _(v)+80

This will allow both the virtual and actual objects respective positionsto therefore be defined in both the actual and virtual coordinate spacessimultaneously. Once the correlation is determined the actual andvirtual coordinate spaces become coupled and the result in the formationof a common coordinate space that may be used to register virtual andactual objects. It should be noted that these virtual and actual objectscan be superimposed in the common coordinate space (e.g., they canoccupy the same coordinates simultaneously).

According to one aspect of the present application, using a handheldthree dimensional (3D) surface scanner, such as the 3D scanner 309, afull or nearly full array scan of a patient's surface can be achieved,as opposed to 1D line or a 2D grid of point depths with the conventionalapproaches. This may provide an order of magnitude greater pointinformation than the surface tracing methods used in conventionalapproaches. Using a dense point cloud provided by the 3D scanner 309,this point cloud may be mapped to the extracted surface of the MR/CTvolumetric scan data (e.g., the pre-op image data 354) to register thepatient's physical position to the volumetric data. The tracking system321 (e.g., part of the navigation system 205) has no reference to thepoint cloud data. Therefore a tool or marker may be provided that isvisible to both the tracking system 321 and the 3D scanner 309. Atransformation between the tracking system's camera space and the 3Dscanner space may be identified so that the point cloud provided by the3D scanner 309 and the tracking system 321 can be registered to thepatient space. A transformation similar to or based on thetransformation described in connection with FIG. 5 may be used.

One aspect of the present application provides for registration of thepatient's current surgical position to the imaging data by placing aseries of markers on the patient's head that are visible by a handheld3D scanner, such as the 2D scanner 309. Following the placement of thesetargets, the 3D scanner is used to collect a surface extraction of thehead where the location of the targets can be identified in the 3Dscanner space. To map this space to the imaging data space, theextracted surface can be fitted to the imaging volume surfaceextraction. Then, the marker locations can be identified in the imagingspace and shown to the user for touch point data collection to identifythe markers in the medical navigation space. In another example, themarkers may be directly observable by the tracking system.

The approach of the present application may be similar to touch pointfiducial registration but eliminates the need for tedious placement andimaging of the patient with fiducial markers that are visible in theimaging modality during preoperative imaging. In another example,following the registration of the 3D scanner extracted surface and theimaging volume extracted surface, anatomical features in the imagingdata can be automatically extracted. Then, these locations can beidentified by touching the navigation tool to each location.

The approaches mentioned above may be useful for recover points,pin-less registration, continuous pinless registration. Further, apatient may not need a scan on the day of the medical procedureresulting in eliminating some of the radiation dosage. Placement of themarkers on the patient may be done in the operating room or by technicalteam preparing the patient for surgery. The process may also beperformed backwards (e.g., take fiducials from an MR scan & projectlocation onto patient). The markers or fiducial stickers could also be aline, other material, or any suitable fiducial marker.

Referring to FIG. 6, a flow chart is shown illustrating a method 600 ofregistering a patient for a medical procedure with a medical navigationsystem, such as the medical navigation system 205. Referring to FIG. 7,another flow chart is shown illustrating the method 600 of registering apatient for a medical procedure with a medical navigation system in amore graphical fashion. FIGS. 6 and 7 will now be discussedconcurrently.

The medical navigation system 205 may be used for registering a patientfor a medical procedure with the medical navigation system usingfiducial markers. The fiducial markers may be placed on the patientprior to a 3D scan and the fiducial markers may each have a target foruse with a tool, such as a pointer tool. In another example, thefiducial markers may be directly observable by the tracking system andno pointer tool may be needed. In another example, the markers may bedirectly observable by the tracking system and may be attached to aMayfield clamp. The medical navigation system may include a 3D scanner,such as 3D scanner 309, a tracking system, such as tracking system 321,a display, such as display 311, and a controller (e.g., processing unit300) electrically coupled to the 3D scanner 309, the tracking system321, and the display 311. The controller may include a processor (e.g.,processor 302) coupled to a memory (e.g., memory 304) and the controllermay be configured to execute the method 600.

The method 600 may be a method of registering a patient for a medicalprocedure with a medical navigation system using fiducial markersvisible by a three dimensional (3D) scanner of the medical navigationsystem. The fiducial markers may be placed on the patient prior to a 3Dscan and the fiducial markers may each have a target usable with apointer tool visible by a tracking system of the medical navigationsystem.

At a first block 602, fiducial markers are placed on the patient,indicated by reference 612 in FIG. 7. In one example, the patient has atleast three fiducial markers placed on the patient after the previousscan during which the preoperative image data was saved but prior to the3D scan. In the example shown in FIG. 7, four fiducial markers have beenplaced on the patient's head. In another example, at least threefiducial markers may be placed on the patient on an area of the patientcorresponding to the saved medical image data (e.g., if the savedmedical image data pertains to a patient's head, the fiducial markersmay be placed in an appropriate area of the head where the medicalprocedure will be performed). In one example, the fiducial markersinclude fiducial stickers. The fiducial markers may include aretro-reflective area visible by the 3D scanner and the preoperativeimage data, indicated by reference 614 in FIG. 7, does not have toinclude the fiducial markers. In one example, the fiducial markers mayeach have a target that is visible by the tracking system. In oneexample, the target includes a divot for receiving the tip of thepointer, indicated by reference 615 in FIG. 7.

At a second block 604, the method 600 generates and receives 3D scandata from the 3D scanner 309 representative of a 3D scan of at least aportion of the patient. The 3D scan includes the fiducial markersvisible by the 3D scanner. The 3D scanner extracted surface is indicatedby reference 616 in FIG. 7.

Next, at a block 606, the method 600 loads saved medical image data,which includes saved medical data including preoperative image datasaved during a previous scan of at least a portion of the patient. Atthis stage, or later one, the method 600 may also extract an imagingsurface from the imaging volume of the saved medical image data,indicated by reference 618 in FIG. 7. In one example, the saved medicalimage data includes at least one of magnetic resonance (MR) coordinatestaken from a MR scan or computed tomography (CT) coordinates taken froma CT scan. The preoperative image data may include data from at leastone of computerized tomography (CT) images, magnetic resonance imaging(MRI) images, positron emission topography (PET) images,contrast-enhanced CT images, X-ray images, or ultrasound images.

Next at a block 608, the method 600 generates and receives position datafrom the tracking system based on the target for each of the fiducialmarkers. In the example where the target includes a divot for a pointertool, the generating and receiving position data from the trackingsystem includes a location of the pointer tool when a tip of the pointertool is placed on the target for each of the fiducial markers, indicatedby reference 620 in FIG. 7. In other words, the surgeon or technicianperforming the method 600 holds the pointer tool with a tip of thepointer tool in each of the divots so that the tracking system canregister the position of the pointer tool by observing the positions ofthe markers on the pointer tool, and consequently the position of thetarget is known. While the example of an optical tracking system isused, the tracking system may include any one of an optical trackingsystem, an electromagnetic tracking system, and a radio frequencytracking system with appropriate markers being substituted.

Next, at a block 610, the method 600 performs a transformation mappingto create a single unified virtual coordinate space based on the 3D scandata, the position data, and the medical image data, and updatesregistration data of the medical navigation system based on thetransformation mapping. In one example, the transformation mapping firstincludes a surface matching calculation using a 3D scanner point cloudbased on the 3D scan data and at least one of the MR and CT coordinates,indicated by reference 622 in FIG. 7. The transformation mapping mayfurther include registering the tracking system to create a singleunified virtual coordinate space for the 3D scanner point cloud, atleast one of the MR and CT coordinates, and the position data from thetracking system based on the locations of the markers, for example whenthe tip of the pointer tool is placed on the targets. In one example,registering the tracking system to the aligned surfaces from the 3Dscanner point cloud based on the 3D scan data and at least one of the MRand CT coordinates may be performed using a point wise correspondenceapproach.

While the blocks of FIG. 6 are shown in a particular order for thepurpose of example, the blocks 602, 604, 606, 608, and 610 need not beexecuted in the exact order shown and suitable modifications may be madeto this order, an example of which is shown below in connection withFIG. 8.

Referring now to FIG. 8, another flow chart is shown illustratinganother example method 800 of registering a patient for a medicalprocedure with a medical navigation system, similar to the method 600discussed in connection with FIGS. 6 and 7.

At a first block 802, magnetic resonance (MR) image scan data iscollected. The collected MR scan image data may be similar to the savedmedical image data loaded at block 606 of method 600.

Next, at a block 804, a surface extraction is performed from the MR datato generate a point cloud, which may be part of the transformationmapping performed at block 610 in method 600.

Next, at a block 806, a point cloud of the patient and reference array(e.g., pointer shown at 615 in FIG. 7) may be generated. The point cloudgeneration may be performed using data generated by the handheld 3Dscanner 309, discussed below in connection with FIGS. 9-15.

Next, at a block 808, the location of the reference array in the pointcloud is identified. In one example, the medical navigation system 205may have stored data that allows the system to recognize the referencearray, such as the pointer, in an image scanned by the 3D scanner 309.In one example, the reference array may have three dimensional featuresthat are recognizable in an image scanned by the 3D scanner 309,allowing the medical navigation system 205 to find the reference arrayin the image.

Next, at a block 810, the location of the navigation system visiblemarkers may be determined in the point cloud. In one example, once themedical navigation system has determined the location of the referencearray (e.g., at block 808), finding the visible markers on the referencearray may be a fairly simple task since the reference array has aspatial configuration known by the medical navigation system 205.

Next, at a block 812, the transformation between the navigation markerlocations in the 3D scanned point cloud and the navigation markerlocations seen by the navigation system may be calculated.

Next, at a block 814, the navigation space transform may be applied tothe 3D point cloud to bring points from the 3D scanner 309 space intothe navigation space.

Finally, at a block 816, the MR extracted surface is registered to the3D scanner 309 point cloud. Blocks 812, 814, and 816 may be similar toand/or part of block 610 performed in method 600. In one example, themethods 600, 700, and/or 800 may employ an Iterative Closest Point (ICP)approach to calculate the registration transformation, such as thatdetailed in “A Method for Registration of 3-D Shapes” by Paul J. Besland Neil D. McKay, IEEE Transactions on Pattern Analysis and MachineIntelligence, pp. 239-256, VOL. 14, No. 2, February 1992, the entiretyof which is hereby incorporated by reference. However, any suitableapproach may be used depending on the design criteria of a particularapplication.

The method 600 shown in FIG. 6 and FIG. 7 and method 800 shown in FIG. 8is shown as an example to illustrate the context of the 3D scanner 309,which is described in more detail below in connection with FIGS. 9-15.However, any suitable method may be used that employs the scannerdiscussed below.

Referring now to FIG. 9, a left side view of a handheld scanner 900 isshown. FIG. 10 shows illustrates a front view of the handheld scanner900. FIG. 11 illustrates a rear view of the handheld scanner 900. FIG.12 illustrates a top view of the handheld scanner 900. FIG. 13illustrates a solid perspective view showing the left side of thehandheld scanner 900. FIG. 14 illustrates a solid perspective viewshowing the right side of the handheld scanner 900. FIG. 15 illustratesa solid perspective view showing the left side of the handheld scanner900 being held by a hand. FIGS. 9-15 are now discussed concurrently.

FIGS. 9-15 show a handheld scanner 900. In one example, the handheldscanner 900 may be used for registering a patient for a medicalprocedure with a medical navigation system, such as the medicalnavigation system 205. The handheld scanner 900 has a housing 902. Thehousing 902 may have a main body portion 904 having a first end 906 anda second end 908. The housing 902 may further have a handle portion 910having a first end 912 and a second end 914. The second end 914 may beattached to the second end 908 of the main body portion 902 with abridge portion 916.

Internally, the handheld scanner 900 may have a circuit board containedin the housing 902, a processor connected to the circuit board, anoptional power supply module connected to the circuit board, a lightemitter 926 contained in the main body portion 904 and connected to thecircuit board, a light detector 924, 928 contained in the main bodyportion 904 and connected to the circuit board, and a button 918connected to the circuit board and located on the second end 914 of thehandle portion 910. The button 918 is engageable by a thumb of a hand920 holding the handle portion 910 (see FIG. 15). In one example, thebutton 918 is non-latching and the scanner 900 is activated to scanwhile the button 918 is held in a depressed position. In anotherexample, the button 918 is latching and is engaged and disengaged with apress of the thumb. While the inside of the scanner 900 is not shown,the scanner 900 may have a control and processing unit having a similarstructure to the unit 300 shown in FIG. 3 including a processor, memory,communications interface, I/O interface, storage, the power supplymodule, the button 918, the light emitter 926, and the light detector924, 928, as well as other suitable components.

The handheld scanner 900 has a number of features on its underside,visible in FIGS. 13-15. In one example, the features may include a clearwindow or cutout where the light emitter 926, the light detector 924,928, and a visible light projector 922 are mounted. The visible lightprojector 922 may be contained in the main body portion 904 andconnected to the circuit board for projecting visible light on thepatient allowing a user of the handheld scanner 900 to aim the handheldscanner 900. In one example, the visible light projector 922 includes alaser pointer showing a center of a field of view of the scanner. Inanother example, the visible light projector 922 displays a shape on thepatient that indicates a direction of scan of the handheld scanner 900and a field of vision of the handheld scanner 900. While two examples ofthe visible light projector are provided, any suitable visible lightprojector may be used that aids the user of the handheld scanner 900 toaim the scanner 900 while performing a scan.

Light emitter 926 may project light onto a subject or patient and lightdetectors 924, 928 may detect light reflected from the surface of thepatient or subject. In one example, the handheld scanner 900 may be aninfrared (IR) based scanner with the light emitter 926 emitting IR lightand the light detectors 924, 928 detecting IR light. In another example,the scanner 900 may be a structured light scanner. In another example,the scanner 900 may be a 3 dimensional (3D) scanner. While some examplesare provided, light emitter 926 may be configured to emit any suitableband of light and light detectors 924, 928 may be configured to detectany correspondingly suitable bands of light according to the designcriteria of a particular application. For example, light emitter 926 mayemit visible light, light detector 924 may detect visible light, andlight detector 928 may detect IR light. Either of light detectors 924,928 may also function as cameras, depending on the design criteria of aparticular application. In one example, one of the light detectors924,928 may be a digital camera and the other may be a depth sensor.

Further, as shown in FIGS. 13-15 by way of example, 922 represents avisible light projector in a particular location and having a particularshape, 926 represents a light emitter in a particular location andhaving a particular shape, and 924,928 represent light detectors inparticular locations and having a particular shape. However, the visiblelight projector 922, the light emitter 926, and the light detectors924,928 may be located in any suitable position on scanner 900 and mayhave any suitable shape, according to the design criteria of aparticular application.

In one example, the handle portion 910 and the body portion 904 may besubstantially parallel (e.g., within 10 degrees) and the bridge portion916 is substantially perpendicular (e.g., within 10 degrees) to thehandle portion 910 and the body portion 904.

The handheld scanner 900 may further have a communications port locatedin a cut-out of the housing and connected to the circuit board. In oneexample, the communications port may include a universal serial bus(USB) port. In one example, the communications port may include apermanently attached cable 930, shown by way of example in FIGS. 9-15.In the example shown in FIGS. 9-15, the cable 930 is attached to thefirst end 912 of the handle portion 910. Where a communications port forreceiving a removable communications cable is placed on the scanner 900,the port may be located at the first end 912 of the handle portion 910or any other suitable location.

In another example, the handheld scanner 900 may have a battery coupledto the power supply module and located in the housing 902 and a wirelesscommunications component located in the housing and connected to thecircuit board. In this example, the handheld scanner 900 may be wirelessand may communicate wirelessly with a computer, such as communicationsinterface 310 of control and processing unit 300 of the medicalnavigation system 205. In one example, the wireless communicationscomponent may operate using Bluetooth, WiFi, and Zigbee, or any othersuitable existing or yet to be developed wireless communicationsstandard. In the example shown in FIGS. 9-15, the handheld scanner 900has a physical cable 930 that provides power and communications to thehandheld scanner 900. In this example, the power supply module locatedin the housing 902 may serve to relay the power provided over the cable930 to the circuit board and optionally regulate and/or control thepower provided to the circuit board from the cable 930, however thepower supply module is optional and may not be needed where the cable930 is configured to directly supply power to all electronics of thehandheld scanner 900.

Additionally, the handheld scanner 900 may have indicators 930, 932located on the front side. In one example, indicators 930, 932 may belights such as light emitting diodes (LEDs). In one example, indicator930 illuminates to indicate a power-on mode of the scanner 900 andindicator 932 illuminates to indicate that the scanner 900 is currentlyoperational and is in the progress of scanning. While examples of theindicators 930, 932 are provided, any number of indicators may be usedto indicate any desired operational states of the scanner 900 dependingon the design criteria of a particular application.

The specific embodiments described above have been shown by way ofexample, and it should be understood that these embodiments may besusceptible to various modifications and alternative forms. It should befurther understood that the claims are not intended to be limited to theparticular forms disclosed, but rather to cover modifications,equivalents, and alternatives falling within the spirit and scope ofthis disclosure.

1. A structured light handheld three-dimensional (3D) scanner for use inregistering a patient for a medical procedure with a medical navigationsystem, the handheld 3D scanner comprising: a housing having: a mainbody portion having a first end and a second end; and a handle portionhaving a first end and a second end with the second end attached to thesecond end of the main body portion with a bridge portion; a circuitboard contained in the housing; a processor connected to the circuitboard; a light emitter for emitting structured light, the light emitterbeing contained in the main body portion and connected to the circuitboard; a light detector contained in the main body portion and connectedto the circuit board; and a button connected to the circuit board andlocated on the second end of the handle portion, the button engageableby a thumb of a hand holding the handle portion.
 2. The handheld 3Dscanner according to claim 1, wherein the button is non-latching and thescanner is activated to scan while the button is held in a depressedposition.
 3. The handheld 3D scanner according to claim 1, wherein thebutton is latching and is engaged and disengaged with a press of thethumb.
 4. The handheld 3D scanner according to claim 1, furthercomprising: a power supply module connected to the circuit board.
 5. Thehandheld 3D scanner according to claim 4, further comprising: a batterycoupled to the power supply module and located in the housing.
 6. Thehandheld 3D scanner according to claim 1, further comprising: a visiblelight projector contained in the main body portion and connected to thecircuit board and for projecting visible light on the patient allowing auser of the handheld 3D scanner to aim the handheld 3D scanner.
 7. Thehandheld 3D scanner according to claim 6, wherein the visible lightprojector includes a laser pointer showing a center of a field of viewof the scanner.
 8. The handheld 3D scanner according to claim 6, whereinthe visible light projector displays a shape on the patient thatindicates a direction of scan of the handheld 3D scanner and a field ofvision of the handheld 3D scanner.
 9. The handheld 3D scanner accordingto claim 1, wherein the handheld 3D scanner is an infrared (IR) basedscanner with the light emitter emitting IR light and the light detectordetecting IR light.
 10. The handheld 3D scanner according to claim 1,wherein a longitudinal axis of the handle portion and a longitudinalaxis of the body portion are substantially parallel and the bridgeportion connects the handle portion and the body portion.
 11. Thehandheld 3D scanner according to claim 10, wherein the light emitter andthe light detector are positioned along the longitudinal axis of thebody portion.
 12. The handheld 3D scanner according to claim 1, furthercomprising: a communications port located in a cut-out of the housingand connected to the circuit board.
 13. The handheld 3D scanneraccording to claim 12, wherein the communications port includes auniversal serial bus (USB) port.
 14. The handheld 3D scanner accordingto claim 1, further comprising: a cable connected to the circuit boardand protruding from the first end of the handle portion.
 15. Thehandheld 3D scanner according to claim 1, further comprising: a wirelesscommunications component located in the housing and connected to thecircuit board.
 16. The handheld 3D scanner according to claim 15,wherein the wireless communications component operates using one ofBluetooth, WiFi, and Zigbee, and communicates with a computer operatingwith a medical navigation system.
 17. The handheld 3D scanner accordingto claim 1 wherein the light detector includes a distinct infrared (IR)sensor and a distinct digital camera.
 18. The handheld 3D scanneraccording to claim 1, further comprising: a first indicator lightlocated on the housing and illuminating to indicate a power-on mode ofthe handheld 3D scanner.
 19. The handheld 3D scanner according to claim1, further comprising: a second indicator light located on the housingand illuminating to indicate a scanning mode of the handheld 3D scanner.20. The handheld 3D scanner according to claim 1, wherein the handheld3D scanner is operable for capturing point cloud data.